J. Agric. Food Chem. 2009, 57, 5783–5789
5783
DOI:10.1021/jf9009153
Distinguishing Chinese Star Anise from Japanese Star Anise Using Thermal Desorption-Gas Chromatography-Mass Spectrometry MELANIE-JAYNE R. HOWES,* GEOFFREY C. KITE, AND MONIQUE S. J. SIMMONDS Royal Botanic Gardens, Jodrell Laboratory, Kew, Richmond, Surrey, TW9 3AB
The volatile compounds from the pericarps of Illicium anisatum L., Illicium brevistylum A.C.Sm., Illicium griffithii Hook.f. & Thomson, Illicium henryi Diels, Illicium lanceolatum A.C.Sm., Illicium majus Hook.f. & Thomson, Illicium micranthum Dunn, and Illicium verum Hook.f. were examined by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). The volatiles desorbed from the pericarps of I. verum (Chinese star anise), the species traded for culinary purposes, were generally characterized by a high proportion of (E)-anethole (57.6-77.1%) and the presence of foeniculin; the latter was otherwise only detected in the pericarps of I. lanceolatum. In the pericarps of all other species analyzed, the percentage composition of (E)-anethole was comparatively lower (e16.0%). The volatiles desorbed from the pericarps of the toxic I. anisatum (Japanese star anise) were characterized by the presence of asaricin, methoxyeugenol, and two other eugenol derivatives, none of which were detected in any of the other species examined. TD-GC-MS enables the direct analysis of the volatile components from the pericarps of Illicium and can assist with differentiating the fruits of I. verum from other species of Illicium, particularly the more toxic I. anisatum. KEYWORDS: Star anise; Illicium; thermal desorption; gas chromatography-mass spectrometry; GC-MS; essential oil; anethole; fruit
INTRODUCTION
Star anise is defined as the dried composite fruit of Illicium verum Hook.f. (1). I. verum is also known as Chinese star anise, and it is widely used as a condiment for culinary purposes and as an infusion for its reputed sedative and carminative properties. In contrast, consumption of “false” star anise, Illicium anisatum L. (synonyms Illicium japonicum Sieb. and Illicium religiosum Sieb. & Zucc.; also known as Japanese star anise or shikimi fruit), has been associated with serious adverse effects including emesis and diarrhea, bradycardia, hallucinations, rhabdomyolysis, and convulsions (2-4). There is confusion over the common names for “star anise” (5) and, because of their similar morphology, misidentification of Chinese and Japanese star anise (I. verum and I. anisatum, respectively) can easily occur. Several reports have been documented in Europe and America that describe clinical toxicity, particularly neurological adverse effects, in both adults and infants that have consumed star anise often prepared as teas, and in some cases, the observed adverse effects could be attributed to contamination of I. verum with I. anisatum (2). Since the U.S. Food and Drug Administration (FDA) has received reports of seizures and other neurological effects associated with the consumption of adulterated Chinese star anise, the FDA issued a warning advising consumers not to drink teas prepared from star anise fruits (2). It is therefore essential that I. verum fruits are distinguished from the fruits of more toxic species of Illicium prior *To whom correspondence should be addressed. Tel: 44(0)208 332 3724. Fax: 44(0)208 332 5310. E-mail:
[email protected].
© 2009 American Chemical Society
to their use in food products, and appropriate analytical methods to achieve this aim are required. Sesquiterpene lactones have been isolated from a number of species of Illicium (Illiciaceae), and some of these compounds have been associated with neurotoxicity. Anisatin is a secoprezizaane sesquiterpene isolated from the seeds and carpels of I. anisatum (6) and also from the fruits and leaves of Illicium floridanum J.Ellis (7) and the pericarps of Illicium merrillianum A.C.Sm. (8). Anisatin antagonizes the action of γ-aminobutyric acid (GABA) by acting as a noncompetitive antagonist of GABAA receptors (9, 10). Neurotoxic sesquiterpene lactones, such as anisatin and neoanisatin, may explain the pharmacological basis of the adverse effects associated with the consumption of I. anisatum (11). Fruits of Illicium majus Hook.f. & Thomson are also reported to be toxic since neomajucin and 2-oxo-6dehydroxyneoanisatin, sesquiterpene lactones isolated from the pericarps, have been associated with convulsant effects in vivo (12, 13). Although some sesquiterpene lactones isolated from I. verum (veranisatins A, B, and C) are reported to be neurotoxic and to induce convulsions, they are considered to be less pharmacologically active than anisatin and occur at relatively low concentrations as compared to anisatin in I. anisatum (3, 14, 15). The toxic sesquiterpene lactones can be detected using highperformance liquid chromatography-tandem mass spectrometry (16), and this method can be used to monitor whether potentially toxic star anise is entering the trade. It complements other methods to evaluate the quality and authenticity of star anise based on sensory, macroscopic and microscopic
Published on Web 06/09/2009
pubs.acs.org/JAFC
5784
J. Agric. Food Chem., Vol. 57, No. 13, 2009
characteristics of the fruit, and thin-layer chromatography analysis and gas chromatography (GC)-flame ionization detection analysis of the essential oil (1, 3, 16-18). GC is regarded as a suitable method to assess the quality and authenticity of I. verum essential oil (1, 17), and several studies have described the oil composition (16-20). The major component of I. verum oil is (E)-anethole, and the percentage content for (E)-anethole specified in the British Pharmacopoeia monograph (European Pharmacopoeia monograph 2108) for steam-distilled star anise oil is 86.0-93.0% (1). In contrast, the essential oils from few other species of Illicium have been studied in detail. The essential oils obtained from fruits of I. anisatum and Illicium griffithii Hook.f. & Thomson have been investigated, and the (E)-anethole content occurs at
